Smithsonian Astrophysical Observatory

Science Updates

The Sun glows with a surface temperature of about 5500 degrees Celsius. On the other hand its hot outer layer, the corona, has a temperature of over a million degrees and ejects a wind of charged particles at a rate equivalent to about one-millionth of the moon's mass each year.

The galaxy Arp 220 is ultraluminous (defined as having more than about 300 times the luminosity of our own galaxy) and, at a distance of only about 260 million light-years, is the closest ultraluminous galaxy to our Milky Way.

The Smithsonian Astrophysical Observatory (SAO) is a "research institute" of the Smithsonian Institution. It is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). Because these research activities share Harvard and Smithsonian staff and resources, the links at this website will take you to information posted on the "CfA" pages.